Device for electromagnetically controlling the position off an armature



May 26, 1970 TOSHIO n- ETAL 3,514,674

DEVICE FOR ELECTROMAGNE ALLY CONTROLLING THE POSITION OF AN ARMATUREFiled May 9 1967 s Sheets- Sheet 1 May 26, 1970 TOSHIO ITO ET AL3,514,674

DEVICE FOR ELECTROMAGNETICALLY CONTROLLING THE POSITION OF AN ARMATUREFiled May 9, 1967 3 Sheets-Sheet 2 Fig.2

May 26, 1970 TOSHIO ITO ET AL 3,514,674

DEVICE FOR ELECTROMAGNETICALLY CONTROLLING THE POSITION OF AN ARMATUR'EFiled May 9, 1967 5 Sheets-Sheet S Fig.

MAGNETIC FIUX DENSITY Br I I l l l I l I I I l I I I i ""I |H I I HIMAGNETIC FIEID I I I I I l I I l l I I I I l I I I l I I I l I I I I I--Br .-=i.

3,514,674 DEVICE FOR ELECTROMAGNETICALLY CONTROLLING THE POSITION OFF ANARMATURE Toshio Ito, Toshimoto Okura, and Toshiji Takami, Amagasaki,Japan, assignors to Mitsubishi Denkr Kabushiki Kaisha, Tokyo, JapanFiled May 9, 1967, Ser. No. 637,155 Claims priority, application Japan,May 18, 1966, ll/31,707 Int. Cl. H01h 47/00 US. Cl. 317155.5 ClaimsABSTRACT OF THE DISCLOSURE The disclosed operating device for moving,for example, a movable contact of a current interrupter from its closedposition to its open position and vice versa comprises a pair ofstationary magnetic cores of permanent magnet material disposed inspaced relation to opposed internal Walls of a magnetic housing and amovable armature movably disposed between the stationary cores to movethe movable contact. Each stationary core is surrounded by an excitingcoil having a parallel combination of currentlimiting resistor and asemi-conductor diode. In the closing operation a closing switch isclosed to discharge a charge with one polarity on one of two capacitorsinto both coils through the respective resistor and diode combinations.The particular stationary core by which the armature is to be attractedis completely magnetized because of conduction of the associated diodewhile the other core magnetized oppositely. to the particular core issubstantially completely demagnetized by means of the action of theassociated limiting resistor with the result that the armature is movedto contact the movable contact with the associated stationary contact.Therefore, the armature and hence the movable contact is maintained atits moved position even after deenergization of the coils. In theinterrupting operation, a process reversed from that above described iseffected.

This invention relates in general to an operating device and moreparticularly to such a device utilizing an electromagnet to move anelement to be operated from one to the other of a pair of its positionsand vice versa and to maintain the element at its moved position untilit is desired to return back to its original position.

The conventional type of operating devices referred to is verydisadvantageous in View of the economical standpoint in that meansshould be provided for maintaining elements to be operated in theiroperated state. For example, such an operating device associated with acurrent interrupter and employing an electromagnet has been commonlyrequired to include a mechanical mechanism for anchoring the interrupterto its operated position, in addition to the electromagnet. In theconventional, relatively small-sized switches and the like, such amechanically anchoring mechanism has not been used but the operatingcoil involved has been forced to have a current continuously flowingtherethrough.

It is, accordingly, a general object of the invention to provide a newand improved operating device for moving an element to be operated fromone to the other of its two positions and vice versa, simple inconstruction, compact, light in weight and inexpensive in which amovable part reduces in weight as well as the operative speedcharacteristics are greatly improved.

Briefly, the invention accomplishes the above cited objects by theprovision of an operating device for moving an element to be operatedfrom one to the other of a pair of its position and vice versa,comprising at least one United States Patent 0 operating electromagnetcontrolled by an exciting coil to move the element, characterized by astationary magnetic core member of permanent magnet material disposed ina magnetic circuit around the electromagnet, and means for controllingenergization of the exciting coil to alternately magnetize anddemagnetize the magnetic core member thereby to move the element and tomaintain it at its moved position after deenergization of the excitingcoil.

A current limiter may advantageously be connected in series to theexciting coil to decrease a flow of current through the exciting coilupon demagnetizing the operating electromagnet as compared with thatupon magnetizing the latter thereby to perform the magnetizing anddemagnetizing operations by the common exciting coil.

In a preferred embodiment of the invention the operating device maycomprise a housing made of a magnetic material, a pair of stationarymagnetic core members of permanent magnet material rigidly secured inspaced relationship on the opposed internal wall surfaces of saidhousing, a movable armature member of magnetic material movably disposedbetween said pair of stationary magnetic core member and including acontrol rod controlling the position of said element to be operated, oneexciting coil surrounding each of said stationary magnetic core members,a current limiter means connected in series circuit relationship to eachof said exciting coils, and means for simultaneously energizing both ofsaid exciting coils through said current limiters, said current limitermeans being operative not to limit a flow of a current zfiowing throughone exciting coil associated 'with the particular stationary magneticcore member by which said movable armature member is now to be attractedthereby to permit that stationary core member to be magnetized but tolimit a current flowing through the other exciting coil to such amagnitude that the remaining stationary magnetic core member issubstantially demagnetized.

The invention as its organization and its mode of operation as well asother objects and advantages thereof will become readily apparent fromthe following detailed description when read in conjunction with theaccompanying drawing in which:

FIG. 1 is a side elevational view, in cross section of an operatingdevice constructed in accordance with one embodiment of the invention;

FIG. 2 is a schematic diagram of a circuit which may be used with theoperating device illustrated in FIG. 1, and

FIG. 3 is a graph useful in explaining the principles of the invention.

While the invention will now be described in terms of a currentinterrupter it is to be understood that it is equally applicable to anyother apparatus including an element to be driven from one to the otherof its two positions and vice versa and to be maintained at its drivenposition for any desired interval of time.

Referring now to the drawing and FIG. 1 in particular, there isillustrated an operating device constructed in accordance with theteachings of the invention. An arrangement illustrated comprises ahousing 10 of any suitable magnetic material, an apertured stationarymagnetic core member, or attracting and holding element, 12 made of anysuitable permanent magnet material and rigidly secured to one internalwall surface, in this case, an upper internal wall surface as viewed inFIG. 1 of the housing 10, a stationary magnetic core member, orattracting and holding element, 14 of the same material as the coremember 12 and rigidly secured to the opposed or lower internal wallsurface of the housing 10, and a movable armature member 16 of anysuitable magnetic material movably disposed between the upper and lowerstationary core members 12 and 14. The movable armature member 16 isprovided on that side facing the upper core member 12 with a centralcontrol rod 18 loosely extending through aligned apertures formed inboth the upper core member 12 and the upper wall of the housing andhaving mounted at the extremity an element to be operated, in theillustrated example, a movable contact member 20 of the associatedcurrent interrupter (not shown). The movable contact member 20 isadapted to engage and disengage from a stationary contact member 22opposing to the same. The upper core member 12 may be called a closingstationary core member and the lower core member 14 may be called aninterrupting stationary core member for the reasons as will be apparenthereinafter.

Disposed within the housing 10 are an exciting coil 24 surrounding theupper or closing stationary core member 12 and another exciting coil 26surrounding the lower or interrupting stationary core member 14 as shownin FIG. 1. Further a flange-shaped protrusion 28 made of the samemagnetic material as the housing 10' extends from the lateral internalwall surface of the housing toward the movable armature member 16.

With the arrangement illustrated it will be appreciated that the upperstationary core member 12, the top housing wall, the upper half of thelateral housing wall, the protrusion 28 and the movable armature member16 form a magnetic circuit through which a magnetic flux due to theupper coil 24 flows with a permanent magnet composed of the core member12 disposed in the magnetic circuit. Similarly the lower stationary coremember 14, the bottom housing wall, the lower half of the lateralhousing wall, the protrusion 28 and the movable armature member 16 formanother magnetic circuit including a permanent magnet.

Referring now to FIG. 3 solid curve designates an initial magnetizationcurve along which the material of the upper stationary magnetic core 12may be first progressively magnetized in one direction, for example, ina positive direction and then gradually demagnetized until it issubstantially completely demagnetized and dotted curve designates asimilar curve for the material of the lower stationary magnetic coremember 14 in the case the core is first magnetized in a negativedirection.

In general, if a magnetic field applied to a permanent magnet materialvaries in both magnitude and direction the residual magnetic fluxdensity thereof may have any desired magnitude. For example, if amagnetic field having a strength of H is applied to the closingstationary magnetic core member 12 through suitable energization of theclosing coil 24 then the core member will have a residual flux densityof B while a magnetic field having a strength of '-H will result in thecore member 12 being substantially completely demagnetized or having thenull residual flux density. Therefore alternate switching of thestationary magnetic core member 12 between its magnetized andnon-magnetized or demagnetized states permits the movable armaturemember 16 to be alternately attracted to and released from thestationary core member 12. This is true in the case of the interruptingstationary magnetic core member 14. It is, however, to be noted that theinterrupting core member 14 should be put in its magnetized state quitereversed from the closing core member 12.

More specifically, upon closing the associated current interrupter (notshown), the closing coil 24 is energized such that it establishes in thematerial of the closing stationary magnetic core member 12 a magneticfield (H having such magnitude and direction that the core member 12 hasa residual magnetic flux density of B while at the same time theinterrupting coil 26 is energized such that it establishes in thematerial of the interrupting stationary magnetic core member 14 amagneitc field (H having such magnitude and direction that the core mem-4 her 14 has the null residual flux density (see FIG. 3). Under theseconditions, the movable armature member 16 is released from theinterrupting core member 14 to be permitted to be attracted by theclosing core 12 thereby to close the associated interrupter throughcontacting of the movable contact 20 directly connected to the controlcore rod 18 with the stationary contact 22. After the deenergization ofboth the coils 24 and 26 the movable armature member 16 is maintained incontact with the closing core member 12 to hold the interrupter closeuntil the subsequent interrupting operation is performed.

If the closed interrupter is to be open, an operation reversed from theclosing operation just described is performed. More specifically, theinterrupting coil 26 is energized such that it establishes in thematerial of the core member 14 a magnetic field (=-H having suchmagnitude and direction that the core member 12 has a residual fluxdensity of B while at the same time the closing coil 24 is energizedsuch that it establishes in the material of the closing core member 12 amagnetic field (-H having such magnitude and direction that the coremember 12 has a null residual flux density (see FIG. 3). This permitsthe movable armature 16 to be released from the upper core 12 and tocontact the lower core 14 thereby to open the interrupter. Then thearmature holds the interrupter in its open position after deenergizationof the coils 24 and 26.

In order to repeat the closing and interrupting operations as abovedescribed, the closing and interrupting coils 24 and 26 can bealternately driven into their predetermined energized states under whicheach coil alternately establishes in the material of the associatedstationary magnetic core a magnetic field having respectively suchmagnitudes and directions that the core is magnetized and demagnetizedrespectively. Then with the coils driven in such energized states, theclosing and interrupting operations are alternately performed and theassociated current interrupter is alternately held in its closed andopen positions after deenergization of the coils. The operating deviceillustrated in FIG. 1 can be effectively operated as above described bymeans of an electric circuit shown in FIG. 2.

As shown in FIG. 2, the closing coil 24 has one end connected to oneterminal of any suitable source 30 of alternating current and the otherend connected to the other terminal of the source through a currentlimiter network generally designated by the reference numeral 32, aseries combination of normally open resettable switch 34 for use in theclosing operation, a charging semiconductor diode 36 and a limitingresistor 38. The serially connected switch and diode 34 and 36 areelectrically connected in parallel to a similar serial combinationcomprising a normally open, resettable switch 35 for use in theinterrupting operation and a semiconductor diode 37 with both diodespoled reversely from each other. The current limited network 32 is shownas comprising a current limiting resistor R and a unidirectionalconduction element or a semiconductor diode D connected in parallel toeach other.

Similarly the interrupting coil 26 has one end connected to the oneterminal of the source 30 through a current limiter network 33 of thesame construction as the network 32 and the other terminal connected tothe other terminal of the source 30 through the abovementioned parallelcombination of serially connected switches and diodes, and the resistor38. Since the limiter network 32 and 33 are of the same construction thecomponents of the network 33 are designated the same referencecharacters sufiixed with the numeral 2 rather than 1.

A capacitor 40 is connected between a junction of the switch and diode34 and 36 and the source 30 while another capacitor 41 is connectedbetween a junction of the switch and diode 35 and 37 and the source 30.It is noted that the capacitors 40- and 41 are charged with oppositepolarities from the source 30 respectively, as shown in FIG. 2.

The closing operation will first be described in conjunction with FIGS.1 to 3 inclusive. Before the closing operation, the closing stationarymagnetic core member 12 has been substantially completely demagnetizedwhile at the same time the interrupting stationary core member 14 hasbeen in its magnetized state in which it has a residual magnetic fluxdensity of B (see FIG. 3) as will be readily understood from theforegoing description. Also the capacitor 40 has been charged with onepolarity while the capacitor 41 has been charged with opposite polarityfrom the source 30.

Under these circumstances, the switch 34 for use in the closingoperation can be enclosed to permit the charge on the capacitor 40 todischarge. The discharge current from the capacitor 40 flows into boththe closing and interrupting coils 24 and 26. However, since the uppercapacitor side is positive with respect to the lower side, thisdischarge current flows forwardly with respect to the diode D of thecurrent limiter network 32 of the coil 24 to cause it to short circuitthe resistor R whereas the current flows reversely with respect to thediode D of the current limiter network 33 for the coil 26 to render itnon-conducting whereby the resistor R of the network 33 remains seriallyconnected to the coil 26. Therefore, the closing coil 24 has flowingtherethrough a current suflicient to produce in the material of theclosing core member 12 a magnetic field having a magnitude of H formagnetizing the latter to saturation, but the interrupting coil 26 hasflowing therethrough a current reduced in magnitude by the resistor R soas toestablish a magnetic field having a magnitude of H in the materialof the interrupting core member 14. In this connection it is to be notedthat the resistor R should have a magnitude of resistance capable ofestablishing in the magnetic core material 14 a magnetic field having amagnitude of H in which the residual magnetic flux density of the core14 just decreases from -B to Zero.

As a result, the closing core member 12 has a residual flux density of Bwhile at the same time the interrupting core member 14 completelydemagnetized to have substantially a null residual flux density. Thiscauses the movable armature member 16 to be released from theinterrupitng core member 14 to be attracted by the closing core member12 whereupon the movable contact 20 contacts the stationary contact 22to close the current interrupter. As previously described, theinterrupter is held in its closed position after deenergization of thecoils 24 and 26, through opening of the switch 34.

Upon performing. the interrupting operation, the switch 35 for use inthat operation is closed to permit the capacitor 41 to discharge. As inthe closing operation a discharge current from the capacitor 41 willflow through both the closing and interrupting coils 24 and 26. In thiscase, however, as the capacitor 41 has its polarity opposite to that ofthe capacitor 40 the discharge current flows forwardly with respect tothe diode D of the current limiter network 33 for the interrupting coil26 to conduct it to short circuit the associated resistor R while thecurrent flows reversely with respect to the diode D to render itnon-conducting whereby the associated resistor R remains seriallyconnected to the closing coil 24. Therefore the interrupting coil 26 hasflowing therethrough a current suflicient to produce in the material ofthe interrupting core member 14 a magnetic field having a magnitude of Hfor magnetizing the latter to saturation, but the closing coil 24 hasflowing therethrough a current reduced by the resistor R to such amagnitude that a magnetic field having a magnitude of -H is produced inthe material of the closing core member 12. As the resistor R theresistor R has a magnitude of resistance preselected to impart to themagnetic core material 12 a magnetic field having a magnitude of H inwhich the residual magnetic flux density of the core 12 just decreasedfrom B to zero.

As a result, the interrupting core member 14 has a residual flux densityof -B,. while at the same time the closing core member 12 isdemagnetized to have substantially a null residual flux density. Thispermits the movable armature member 16 to be separated from the closingcore 12 to contact the interrupting core 14 thereby to disengage themovable contact 20 from the stationary contact 22 resulting in aninterruption of the interrupter. As previously described, theinterrupter is held in its open position after opening of the switch 35and until the subsequent closing operation is performed.

From the foregoing, it will be appreciated that by alternatelydischarging the charges of alternate polarity on the capacitors 40 and41 intothe closing and interrupting coils '24 and 26, each of theclosing and interrupting stationary core members 12 and 14 can berepeatedly magnetized and demagnetized. The magnetization anddemagnetization of both cores causes the movable armature 16 to move ineither of the directions thereby to perform the closing or interruptingoperation of the associated current interrupter as well as maintainingthe latter in its closed or open position until the subsequentinterrupting or closing operation is performed.

If a movable armature attracted by the associated stationarymagneticcore is to be separated from the latter, it has been previously requiredto provide a pulling-apart or an interrupting coil, in addition to aclosing coil. The invention, however, comprises means for exerting onsuch a movable armature an opposing force in a direction opposite to thedirection of attraction. In addition, upon pulling apart the armaturefrom the closing stationary core, a current flows through the closingcoil in a direction reverse from in the closing operation. This flow ofcurrent through the coil in the reversed direction causes the residualmagnetism in the stationary core to be balanced out by a magnetic fluxdue to the same, whereby the armature can be automatically separatedfrom the stationary core by the action of the opposing force as abovedescribed. As already mentioned, the current limiter network associatedwith the closing stationary core by which the armature was previouslyattracted is effective for limiting an interrupting current flowingthrough the closing coil to such a magnitude that a magnetic flux inthat stationary core has an appropriately small value approximating zerowithout the core magnetized in the opposite direction. This is true inthe case of the interrupting stationary core in the closing operation.

In FIG. 2, it is noted that a normally open contacts S or S -are shownas being connected across the unidirectional conduction element or diodeD or D by dot-anddash line respectively. This means that the contacts Sor S may be used in place of the diode D or D With the contacts S and Sused, they should be arranged such that upon closing the switch 40, thecontacts S are closed while the contacts S remain open whereas, uponclosing the switch 41, the contacts S are closed while the contacts Sremain open.

While the invention has been illustrated and described with reference tocertain preferred embodiments thereof it is to be understood thatvarious changes in the detail of constructions and the combination andarrangement of parts may be resorted to without departing from thespirit and scope of the invention. For example, either the closing coreand coil assembly 12, 24 or the interrupting core and coil assembly 14,26 may be replaced by springloaded operating means to perform theassociated operation. Also the present device may be equally applied toany element subject to first drive to perform a first operation and tosubject to second drive to perform a second operation.

What we claim is:

1. A device for electromagnetically controlling the position of anarmature comprising: a first magnetic circuit including a firstferromagnetic attracting and holding element, and a first exciting coilmagnetically coupled to said first ferromagnetic attracting and holdingelement; a second magnetic circuit including a second ferromagneticattracting and holding element, and a second exciting coil magneticallycoupled to said second ferromagnetic attracting and holding element; amoveable armature disposed between said first and second ferromagneticattracting and holding elements movable to a first position in responseto encrgization of said first magnetic circuit and to a second positionin response to energization of said second magnetic circuit; andelectric circuit means connected to said first and second coils foralternatively sup-. plying current to one of said exciting coils torender its corresponding ferromagnetic attracting and holding elementeffective to move said armature to one of said first and secondpositions and hold it therein while simultaneously supplying a lesseramount of current to the other of said exciting coils to remove anyresidual magnetism remaining in the other of said ferromagneticattracting and holding elements when said electric circuit means isconnected to a source of potential.

2. A device according to claim 1; wherein said first and secondferromagnetic attracting and holding elements comprise first and secondmagnetic core elements, respectively.

3. A device according to claim 1; wherein said electric circuit meansincludes first and second current limiting circuits each connected inseries with said first and second exciting coils, respectively; saidfirst and second current limiting circuits each comprising a currentlimiting impedance element connected in parallel with a diode.

4. A device according to claim 1; wherein said electric circuit meansincludes first and second current limiting circuits each connected inseries with one of said first and second exciting coils, respectively;said first and second current limiting circuits each comprising acurrent limiting impedance element connected in parallel with a switch.

5. A device according to claim 1; wherein said first and second excitingcoils are connected in parallel; and wherein said electric circuit meansincludes first and second normally open switches, a first capacitorresponsive to the closing of said first normally open switch to supply afirst discharge current to both said exciting coils, a second capacitorresponsive to the closing of said second normally open switch to supplya second discharge current to both said exciting coils in a directionopposite to that of said first discharge current, and current limitingmeans for successively limiting the flow of current through alternateexciting coils in accordance with the alternate closing and opening ofsaid first and second normally open switches. i

References Cited UNITED STATES PATENTS 2,317,888 4/ 1943 Cypser 3171232,954,512 9/ 1960 Hardison 317-151 3,445,729 5/1969 McNulty 317-1233,202,886 8/ 1965 Kramer 335-234 FOREIGN PATENTS 643,832 6/1962 Canada.

I. D. MILLER, Primary Examiner C. YATES, Assistant Examiner U.S. Cl.X.R. 335-234

